Sea level rise

John Fairburn (The Weekend Sun, August 9) is correct on just one point: Rob Colmore and I “disagree sharply”: I believe in the basic science of climate change. To disprove this “propaganda”, he cites a three metre sea level rise prediction but, from his own and family’s observations of “tide heights for over seventy years, the verdict is in. Absolutely no change!”

Where does his “three metres” come from? According to NIWA sea level rise over the past 70 years has averaged only 17cm - an amount almost impossible to detect by casual observation.

More to the point, the global rate of rise since 1900 has virtually doubled to 3.4mm/year and most current projections indicate this figure will have increased five-fold by the end of this century, likely to result in a rise of at least one metre – and still going strong. (See NIWA’s graph representing nine separate studies.)

The main uncertainties are the unknown degree of future global emission reductions and the increasing melting rates of the Antarctic and Greenland ice sheets – the subject of intensive international research, especially by New Zealand, due to the obvious global implications.